Conventionally, air conditioners for vehicles with a composite heat exchanger capable of exchanging heat between plural kinds of fluids are disclosed (see, for example, Patent Documents 1 and 2).
Specifically, Patent Document 1 (JP 3275415 B2) discloses regarding an air conditioner for a vehicle with a composite heat exchanger. The composite heat exchanger includes the combination of a heat exchanger for heating and a heater core. The heat exchanger exchanges heat between a refrigerant discharged from a compressor (high-pressure refrigerant) and a feed air blown into a vehicle interior (hereinafter referred to as a vehicle-interior feed air) to thereby heat the vehicle-interior feed air. The heater core exchanges heat between brine (heating medium) heated by a combustion hot-water heater and the vehicle-interior feed air to thereby heat the feed air.
Patent Document 2 (US 2004/0060316 A1 corresponding to JP 431115 B2) discloses another air conditioner for a vehicle with a composite heat exchanger. The composite heat exchanger includes the combination of the same heat exchanger for heating as that disclosed in Patent Document 1, and a heat core that exchanges heat between an engine coolant (heating medium) for cooling an engine and the vehicle-interior feed air to thereby heat the feed air.
Both Patent Documents 1 and 2, however, only disclose the air conditioner for a vehicle that heats the feed air in the vehicle interior by dissipating heat of the high-pressure refrigerant or heat medium having a higher temperature than that of the vehicle interior by means of the composite heat exchanger. That is, the air conditioner for the vehicle disclosed in each of Patent Documents 1 and 2 is provided with the composite heat exchanger only for heating the vehicle-interior feed air with the heat contained in the high-pressure refrigerant or heat medium, and not for the purpose of exchanging positively heat between the high-pressure refrigerant and the heat medium. The air conditioner disclosed cannot effectively utilize the heat contained in respective fluids.